1. Field of the Invention
The present invention relates to needle guides for use in surgery and more particularly, to a needle guide that can be detached during surgery from its hub.
2. Description of the Prior Art
In the performance of minimally invasive percutaneous surgical procedures, it is necessary to establish the surgical portal with minimal trauma using a spinal needle or similar device. Such procedures may include those performed on deep joints, such as the hip or spine, cardiovascular procedures, such as balloon angioplasty, or any application requiring accurate atraumatic placement of the surgical portal, with subsequent enlargement for the introduction of larger operative instrumentation.
In percutaneous disc surgery, for example, a hypodermic needle is often used in order to confirm proper placement in a deep joint by injecting a radiopaque dye for discography. Typically, a sharp spinal needle is directed toward the intervertebral disc under flouroscopic control and is followed by insertion of successive tubes, or cannulas, of increasing diameter.
Kambin U.S. Pat. No. 4,573,448 describes a method for decompressing herniated intervertebral discs which includes the steps of inserting a hollow needle with a stylet through the patient's skin at a desired location, removing the stylet, introducing a guide wire through the needle, withdrawing the needle while keeping the guide wire in place and subsequently passing a trocar over the guide wire. The guide wire is then removed and a cannula is passed over the trocar. The trocar is removed and a cutting instrument is introduced through the cannula.
An article by J. A. N. Shepperd et al., "Percutaneous Disc Surgery" 238 Clinical Orthopaedics and Related Research 43 (Jan. 1989), describes the use of a discogram needle with a detachable hub which is used in place of a separate guide wire. The discogram needle and probing cannula are inserted into the disc. The needle is retained there as an anchor. The article states that the needle hub is removed to permit withdrawal of the probing cannula, leaving the needle to act as a guide wire. There is, however, no description or suggestion of the means of removing the hub from the needle.
Another known procedure for percutaneous nucleotomy employs a discography needle which fits within an external sheath. The needle is inserted into the intervertebral disc. Following completion of the discography, the needle is withdrawn leaving the sheath in place. Cannulas are then introduced over the external sheath.
There is some risk associated with the insertion of the tubes, or cannulas over a guide wire. If the guide wire is inadvertently moved during the withdrawal of the needle, the subsequent insertion of the cannulas over the guide wire will be imprecise. An object of the present invention is to reduce the risk of inadvertently moving the guide wire when removing the needle. A further object is to provide a needle guide which can be adapted to function as a guide wire for the subsequent insertion of a cannula without removal of the needle once accurately placed. Another object of the present invention is to provide such a needle guide which is simply constructed and simple to use.